i just built another rig for work and its the apogee drive, it loads incredibly well i had pretty low expectations since its on a quad but it currently idles 33 +/-2c across all cores with a MCR320 and loads below 53 with an ambient of 23c

the pump does get a bit hot and if that heat could be cooled it would do a better job but to answer your question it can be used as just a pump just needs a top

Yeah, you should be able to use it as a pump no problem. It's not as efficient as a regular 350 because it has block restriction to work against, but still probably plenty of pumping power for any average to low restriction setup.